You don't need to top up the fork oil, because the level will do nothing, you simply want it above the dampening rod. To make a difference you can either go to a heavier or lighter weight of oil, or re-shim.
Oil level not critical? News to me, used to see a lot of recommendations, at least before USD forks to add until it was 6" from the top of the tubes. I knew a guy who topped them off, rode like a brick until he blew out the fork seals. Ron